A wearable device may be divided into a video see-through type and an optical see-through type according to a structure of a display that outputs image information. The video see-through type corresponds to a type in which an image acquired through a camera and image information provided by a computer are combined and the combined image is provided to a user. Accordingly, the user recognizes surroundings only by means of the image acquired through the camera, so that the user may be cut off from an actual surrounding environment. The optical see-through type corresponds to a type in which a virtual image provided by the computer is projected onto the surrounding environment directly recognized by the user. Accordingly, the user may be in harmony with the surrounding environment.
When a user views an object through a wearable device, the user may feel dizzy and may complain of severe pain, since a depth of a projected image does not change according to a location (short, middle, or long distance) of an actual object even though depth information (or an object distance) on an actual image and depth information on the projected image are different.
Therefore, a need exists for a method and an apparatus for providing a virtual image by using a projection type display unit.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.